Breast cancer impacts 12.2% of women in the United States, with a third of all patients dying from the disease. Approximately half of breast cancer patients elect to have breast conservation surgery (BCS), also known as lumpectomy, as an alternative to mastectomy as a major part of their treatment. A recent study of 994 women diagnosed with ductal carcinoma in situ (DCIS) showed that both treatment strategy (BCS alone, BCS with radiation therapy, or mastectomy) and margin status strongly correlated with long-term ipsilateral disease-free survival, but that positive or close margins following the last surgical treatment significantly reduced 5-year and 10-year ipsilateral event-free survival independent of treatment strategy.
Several approaches are therefore being investigated for the pre-operative and intraoperative estimation of margin sizes as well as for the intraoperative detection of cancer in surgical margins. Methods studied for the estimation of margin sizes include pre-operative CT and MRI and intraoperative ultrasonic imaging with conventional medical ultrasound instrumentation. A number of electromagnetic and optical methods are also being developed for the intraoperative detection of cancer in margins. These include terahertz imaging, Raman spectroscopy, optical coherence tomography, and diffuse reflectance spectroscopy. Intraoperative pathology methods currently being used for margin assessments include touch preparation cytology and frozen section analyses. These methods have limitations, however, including the requirement for an on-site trained pathologist, the inability to identify close margins (touch preparation cytology), and the ability to sample only a small portion of the margin (frozen section analyses).
Since removal of all of the cancer in BCS, and in other cancer surgeries, is critical to preventing local recurrence of the malignancy, surgeons strive to obtain negative margins (cancer free tissues surrounding the tumor). Using current techniques, however, a surgeon cannot determine the pathology of the margins in the operating room, and conventional pathology takes 2-4 days to analyze the specimens. Currently, 30-50% of BCS patients require re-excision due to positive margins, resulting in additional patient suffering and health care costs. Therefore, surgeons urgently need a real-time technique to determine the pathology of surgical margins during cancer surgery.